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A-Z Allergies

Mould allergy

Moulds are microscopic fungi, which, unlike plants, are unable to produce their own food from sunlight and air. They are made up of clusters of filaments, and live on plant or animal matter, which they decompose for their nourishment.

Moulds are among the most widespread living organism, with many different varieties. The common bread mould is a well-known example. Some moulds produce penicillin or other antibiotics, or are necessary for agricultural and food production; others produce potent toxins or are major source of plant disease. Many moulds reproduce by releasing spores in the air, which then settle on organic matter and grow into new mould clusters. These airborne mould spores are far more numerous than pollen grains, and when inhaled can produce allergic symptoms in susceptible individuals.

What is mould allergy?

If you suspect an allergy to moulds, you should see an allergy specialist for allergy testing. Mould allergy can cause respiratory symptoms and hayfever-type problems. If you find that you start sneezing or wheezing when you go into a basement or damp room with old, stored papers and clothes, then it is possible that you are reacting to mould spores. Some people with mould allergy will react in fruit shops and in some heavily planted, shady gardens.

Where are moulds found?

Moulds can be found in most environments, and unlike pollen do not have a strictly limited season. Their growth is encouraged by warmth and high humidity, however, so they are most prevalent during the humid season of the year. Moulds are found out of doors and in the home. They are present in outside air unless there is a cover of snow on the ground, and are especially prevalent in shady, damp areas and on decaying leaves or other vegetation. Mould spores produced outside become widely dispersed through the air, and can enter the home. Other moulds are produced in the home, especially in areas of high humidity such as basements and showers.

What can be done to reduce mould exposure?

Mould sensitive individuals should avoid exposure to areas of high mould growth, such as basements, compost piles, fallen leaves, cut grass, barns and wooden areas. A face mask should be worn when such exposure is unavoidable. In the home, it is important to prevent high levels of humidity. A gauge measuring relative humidity should be obtained, and the level in the house kept below 40%. This can be accomplished by the use of air conditioners and dehumidifiers in the summer, and by preventing over-humidification in the winter. Excess humidity produced by showering or cooking should be removed with an exhaust fan. Mould growing in the home can be killed with various products.

Ways to reduce household mould

Mould will flourish in damp, dark and warm places. Some of the more hardy moulds grow in different, drier situations. The following steps will help to eliminate the major sources of mould or mildew in your home.

Kitchen
• Ensure fruit in fruit-bowls and all refrigerated food has not gone mouldy. Avoid storing fruit at room temperature for more than 72 hours, especially if completely enclosed in plastic.
• Keep the fridge drip-tray clean. Fridges have a collecting ledge, which takes excess moisture inside via a pipe to the underside drip-tray. Both the pipe and the drip-tray (out of sight) can become heavily contaminated with mould. Place one teaspoon of bleach down the pipe every two weeks to prevent this happening.
• Don't let bread go mouldy - keep it in a container suited for the purpose or in the fridge.
• Watch dried fruits and other foods in the pantry. Remove anything before it actually goes mouldy. Keep foods as fresh as possible. Use airtight containers so that smells and any potential moulds are kept contained.

Home Offices

• Piles of papers, books, old newspapers and magazines will absorb moisture and encourage mould growth. They should be discarded if they smell damp or mildewed. Even if they are dried out these items may still retain mould spores.
• Mould can also grow in damp areas on south facing walls particularly in places where the air does not circulate behind furniture. Be aware of this when planning the layout of your office.

Living area and bedrooms
• Ensure the drip-tray of air-conditioners, dehumidifiers and evaporative coolers are free of mould.
• Check any damp walls (especially south-facing) for mildew, especially behind wallpaper. Treat with mould inhibitor, then sealer and then paint. Some brands of paint contain mould inhibitors.
• Avoid more than ten indoor plants and none should be in a greenhouse setting (humid at 20-25 C). An atrium fernery, open to the inside house, will be a source of mould. Keep the potting mix fresh on any indoor plants as this will grow mould spores very readily.
• Do not allow mattresses to stay damp from bed-wetting. If a foam mattress has been wet in the past then it is likely to contain considerable mould and it should be encased completely in plastic. This applies to pillows that have been allowed to get damp from dribbling or mucus. Some of the allergen barrier bedding covers are waterproof, so this is a good option if you have children who are likely to wet the bed.
• Furniture made of leather or cushions containing foam that have been damp at some time will be prone to contamination with mould. Check for a musty smell.
• Carpets tend to hold any mould spores that have collected in the house, and they favour the growth of mould, especially if the carpet has been damp at some stage. Removing musty carpet is a better option than cleaning it. Many methods of carpet cleaning will actually encourage mould growth by leaving the carpets slightly damp. The carpet never completely dries out after these processes.
• Frequent use of a vapouriser to treat children's asthma or croup will create dampness, which will allow mould to thrive on walls, bedding and furniture. Allow the room to dry out in between uses. Use a dehumidifier in the room after using a vapouriser and also open the windows and allow as much fresh air to pass through the room as possible.

Bathroom
• Keep it well ventilated and dry. Fitting an extractor fan may be necessary.
• Remove face cloths, towels etc. which have a musty smell, and replace with fresh ones. Towels and face cloths should be washed every couple of days and should be dried in between use. A heated towel rail is ideal, or put the towels outside in the sun to dry.
• Don't allow mould to form on the shower recess, shower curtain or walls and keep your eye on traps around the bath and basin areas.

Outside the house
• If the house has a musty smell and evidence of damp, ensure that storm-water drainage takes water away from the house, and that spouting is working correctly to stop water running down the outside wall. Clean spouting regularly. Look for rising damp in walls - they may need a new damp course. If there is damp beneath the house, clear to allow as much ventilation under the house as possible, and treat mould on under-flooring or bearers.
• Avoid heavy vegetation around and over the house and remove ivy and other climbing plants.
• Keep the yard free of fallen leaves and other garden debris. Ensure the compost heap is well covered, well away from the house and not easily accessible by children.
• Avoid the use of bark and other mulches around plants and in gardens. This will encourage significant levels of mould growth.
• Garden water features are also a potential trap, so ensure that they are well cleaned and aerated. Moving water is generally not so much of a problem.